PRESIDENTIAL ADDRESS. 641 
atrived at a condition in which each one is absolutely dependent for its exist- 
ence on its connection with the rest of the organism and is also essential to the 
well-being of every other part of the organism. 
This solidarity, this subjection of all selfish activity to a common end, namely 
preservation of the organism, could only be effected by a gradual increase in the 
control of all parts by one master tissue of the body, whose actions were deter- 
mined by impulses arising from sense organs which themselves were set into 
activity by coming events. We thus have with the rise in type a gradually 
rising scale in powers of foresight, in control by the central nervous system, and 
in the solidarity of the units of which the organism is composed. 
In the struggle for existence the rise in type has depended therefore on the 
central nervous system and its servants. Rise in type implies increased range 
of adaptation, and we have seen that this increased range, from the very beginning 
of a nervous system, was bound up with the powers of this system. Whatever 
opinion we may finally arrive at with regard to the types of animals which we 
may claim as our ancestors on the line of descent, there can be no doubt that 
Gaskell is right in the fundamental idea which has guided his investigations 
into the origin of vertebrates. As he says, ‘ the law for the whole animal kingdom 
is the same as for the individual. Success in this world depends upon brains.’ 
The work by this observer which has lately appeared sets forth in greater detail 
than I have been able to give you to-day the grounds on which this assertion is 
based, and furnishes one of the most noteworthy contributions to the principles 
of evolution which have been published during recent years. 
We must not, however, give too restrictive or common a meaning to the 
expression ‘brains’ used by Gaskell in the dictum quoted above. By this word 
we imply the whole reactive system of the animal. In the case of man, as of some 
other animals, his behaviour depends not merely on his intellectual qualities or 
powers, to which the term ‘ brain’ is often in popular language confined, but 
on his position as a member of a group or society. His automatic activities in 
response to his ordinary environment, all those social acts which we ascribe in 
ourselves to our emotions or conscience, are determined by the existence of 
tracts in the higher parts of his brain, access to which has been opened by 
the ruthless method of natural selection and which have been deepened and 
broadened under the influence of the pleasurable and painful impressions which 
are included in the process of education. All the higher development of man 
is bound up with his existence as a member of a community, and in trying to 
find out the factors which will determine the survival of any type of man, we 
must give our attention, not to the man, but to the tribe or community of which 
he is a member, and must try to find out what kind of behaviour of the tribe 
will lead to its predominance in the struggle for existence. 
Political Evolution. 
The comparison of the body politic with the human body is as old as political 
economy itself, and there is indeed no reason for assuming that the principles 
which determine the success of the animals formed by the aggregation of 
unicellular organisms should not apply to the greater aggregations or com- 
munities of the multicellular organisms themselves. It must be remembered 
however, that the principles to which I have drawn your attention are not those 
that determine survival, but those which determine rise of type, what I have 
called success. Evolution may be regressive as well as progressive. Degenera- 
tion, as Lankester has shown, may play as great a part as evolution of higher 
forms in determining survival. The world still contains myriads of unicellular 
organisms as well as animals and plants of all degrees and complexity and of 
rank in the scale of life. All these forms are subordinate to man, and when in 
contact with him are made to serve his purposes. In the same way all mankind 
will not rise in type. Many races will die out, especially those who just fall 
short of the highest type, while others by degradation or differentiation may 
continue to exist as parasites or servants of the higher type. 
Mere association into a community is not sufficient to ensure success ; there 
must also be differentiation of function among the parts, and an entire sub- 
1909. aa 
